Selective recovery of indium from lead-smelting dust

Abstract

Non-ferrous smelting dust, especially lead-smelting dust (LSD), contains percent levels of indium and thus constitutes a novel indium resource. The main difficulty in recovering indium from LSD is the coexisting presence of lead and zinc. In this study, a unique indium separation process was designed, combining techniques that involve washing with a chelant, leaching with acid and precipitation as hydroxide. The majority of the Pb in the LSD was selectively separated during chelant-assisted washing with ethylenediaminedisuccinate (EDDS), while the residual Pb was diminished through an acid leaching treatment with a mixed solution of sulfuric acid and hydrochloric acid. The chelant washing step also ensures a decrease in the raw LSD weight at a ratio of approximately 82 % due to the removal of lead and counterions such as sulfate, and the washing step also minimizes the consumption of corrosive acids in the subsequent step. Selective indium separation from LSD is further complicated by the similarity of the behavior of zinc during the acid leaching step. Therefore, hydroxide precipitation at pH 5 has been introduced as the final step, ensuring the maintenance of zinc as a soluble species in the supernatant and the selective separation of indium (∼ 88 %) as a hydroxide precipitate. KeywordsIndium recovery; Selective separation; Lead-smelting dust; Chelant-assisted washing; Acid leaching, Hydroxide precipitation Chemical Engineering Journal, 277: 219-228, 2015 The original publication is available at: http://dx.doi. org/10.1016/j.cej.2015.04.112 3 IntroductionThe metal indium, particularly as ITO (indium-tin-oxide) thin film, is an industrially important component because ITO is necessary for building electronic devices [1]. ITO is widely utilized for manufacturing liquid crystal displays, plasma displays and solar energy cells [2], which consume approximately two-thirds of the global indium production [1]. One of the resource materials for raw indium is non-ferrous metal ore [3], which is obtained as a by-product of the smelting process of the non-ferrous metal ore [4]. Raw indium deposits are region-specific (i.e., China, Korea, and Russia) [5]. Discrepancies in demand, supply and price are therefore observed. The search for alternate sources of raw indium is vital from the point of view of resource strategy, and this search is focused mostly on the processing of indium-laden waste materials, e.g., ITO scrap [2, 6-8], end-of-life liquid crystal displays [6,[9][10][11] and etching waste [12][13][14].The residue and flue dust from the smelting of non-ferrous metals, such as lead, termed lead smelting dust or LSD hereafter, also includes indium [15] and is expected to be a novel indium resource. Acid leaching is commonly employed for metal smelting from waste resources [16][17][18].Indium recovery from waste material has been reported through the use of acid leaching and hydroxide or sulfide precipitation [2,6,7,[19][20][21]. This approach is frequently criticized both in terms of overall efficiency d...

Cooperative adsorption of critical metal ions using archaeal poly-γ-glutamate

“…(Fig. is converted to undesirable hydroxide precipitates at pH *5 (Sawai et al 2015). This difficulty could be attributed to negligible conformational changes to their separable (water-insoluble) complexes (Fig.…”

Valuable Metals—Recovery Processes, Current Trends, and Recycling Strategies

“…[88] Indium-containing zinc residues are digested in ar eductive leaching process with sphalerite and H 2 SO 4 ,t he subsequent solvent extraction of which furnishes recovery rates > 95 %. [90] [5] Fore xample,l ead and indium can be separated by adding chelators to the hydrometallurgical leaching process of lead smelter dust.…”

“…For example, lead and indium can be separated by adding chelators to the hydrometallurgical leaching process of lead smelter dust. Subsequent acid digestion provides an indium recovery rate of 88 % …”

Wertmetalle – Gewinnungsverfahren, aktuelle Trends und Recyclingstrategien

“…Außer der Gewinnung von Indium als Nebenprodukt der Zinkproduktion sind auch Gewinnungstechnologien für die Blei‐, Kupfer‐ oder Zinnherstellung bekannt . So kann beispielsweise durch die Zugabe von Chelatbildnern zur hydrometallurgischen Laugung von Bleihüttenstaub zunächst eine Blei‐Indium‐Trennung erreicht werden, und durch anschließende Säurelaugung des Rückstands können 88 % des enthaltenen Indiums ausgebracht werden …”